Effect of Initial Bainite Microstructure on Tensile Properties After Long-Term Exposure at Elevated Temperature

2018 ◽  
Author(s):  
Junji Shimamura ◽  
Shusaku Ota ◽  
Tomoyuki Yokota ◽  
Ryuji Muraoka
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
The Other ◽  
Accelerated Cooling ◽  
Oil Sand ◽  
Initial Strength ◽  
Term Operation ◽  
Steel Pipes ◽  
Bainite Microstructure

In the oil sand production field in Canada, steel pipes are used for injecting steam into the sands. Pipes for steam distribution are subjected to high operating temperature such as 350 degrees C for a long time. In this study, in order to insure the reliability of high strength pipe for steam distribution, long-term heating tests were conducted for X80 grade UOE pipe. To simulate the long-term operation at 350 degrees C for 40 years, accelerated tests were conducted at 400 degrees C for up to 4400 hours. The effect of initial bainite microstructure on tensile properties after long-term heat treatment was investigated by using two kinds of steel pipes with different bainite microstructure. One is accelerated cooling (ACC) type, and the other is heating on-line process (HOP) type just after accelerated cooling in plate manufacturing process. It was revealed that strength decrease in ACC type steels produced by only accelerated cooling was mainly governed by decomposition of hard phase MA (Martensite-Austenite constituent) and recovery of dislocations. On the other hand, HOP type steels had small amount of MA and nanometer-sized carbides by applying HOP after accelerated cooling. The HOP type steels had almost the same initial strength in spite of small amount of MA. Fine niobium carbides gave enough precipitation strengthening. Formation of fine niobium carbides was promoted by the addition of niobium. The precipitates were stable after long-term heat treatment at 400 degrees C. It is confirmed that the fine niobium carbides in HOP type steels remained even after long-term heat treatment. The suppression of initial MA also lead to minimize the strength decrease by MA decomposition. Therefore, HOP type steels tend to have higher resistance to the strength decrease after long-term heat treatment.

Mechanical Properties of Newly Developed API X80 Grade HFW Linepipe for Long-Term Exposure at Elevated Temperature

2014 ◽  
Author(s):  
Shunsuke Toyoda ◽  
Sota Goto ◽  
Takatoshi Okabe ◽  
Yasushi Kato ◽  
Satoshi Igi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
High Temperature ◽  
Distribution System ◽  
Weld Seam ◽  
Fatigue Properties ◽  
Oil Sand ◽  
Creep Tests ◽  
Term Operation

API X80 grade UOE double submerged arc-welded pipe has been applied to steam injection oil sand recovery systems to increase the volume of steam to be injected and decrease the installation cost. The pipes for the systems are subjected to high temperature for a long period, such as 350 °C for 20 years. Therefore, it is important to ensure the reliability of the pipes during and after long-term operation. In this study, based on the recent development of high-frequency electric-resistance-welded (HFW) linepipe with a high-quality weld seam, the durability of newly developed API X80 grade HFW linepipe for long-term high-temperature operation was investigated. The change in the microstructure of the pipe body and weld seam was small after exposure to 400 °C and lower temperatures. The tensile strength of the base metal and weld seam after heat treatment with temperatures as high as 400 °C can be determined using the Larson-Miller parameter, which depends on the temperature and holding time of the heat treatment. The newly developed API X80 grade HFW linepipe was considered to have sufficient tensile strength during and after long-term operation at 350 °C for 20 years, similar to API X80 grade UOE pipe. No significant change in the Charpy absorbed energy during long-term heating was observed. Creep tests indicated that the time to rupture at 400 °C or lower exceeded 106 hours, and the creep effect was considered almost negligible at temperatures less than 400 °C. The rupture stress at approximately 350 °C was estimated to be far higher than the typical hoop stress of approximately 200 MPa on the steam distribution system. High-temperature fatigue properties were also measured to ensure reliability under varying stress conditions.

scholarly journals Structural and mechanical defects of materials of offshore and onshore main gas pipelines after long-term operation

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Iryna Danyliuk ◽  
Lyubomyr Poberezhnyi ◽  
Taras Pyrig ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Quantitative Analysis ◽  
Stress Concentration ◽  
Cyclic Loading ◽  
Fatigue Cracks ◽  
Preliminary Deformation ◽  
Term Operation ◽  
Steel Pipes

AbstractThe study has established the main regularities of a fatigue failure of offshore gas steel pipes installed using S-lay and J-lay methods.We have numerically analyzed the influence of preliminary deformation on the fatigue life of 09Mn2Si steel at different amplitudes of cyclic loading. The results have revealed the regularities of formation and development of a fatigue crack in 17Mn1Si steel after 40 years of underground operation. The quantitative analysis describes the regularities of occurrence and growth of fatigue cracks in the presence of a stress concentration.

Determination of Tensile Properties of Power Plant Steels by Testing of Miniature Specimens

2013 ◽  
Author(s):  
Ivan Klevtsov ◽  
Andrei Dedov
Keyword(s):  
Mechanical Properties ◽  
Power Plant ◽  
Flat Plate ◽  
Tensile Properties ◽  
Standard Size ◽  
Term Operation ◽  
University Of Technology ◽  
Miniature Specimens

Long-term operation of the power plant components in the conditions of the creep leads to the degradation of the short-term mechanical properties of the material. Therefore, in order to predict the degree of the metal degradation and integrity of the component the determination of the mechanical properties of the actual component in service material is required. Since the standard tests requiring a significant volume of sample material cannot be applied the technique of the tensile testing of miniature flat plate specimens has been developed in Tallinn University of Technology and described in this paper. The results of the tests of miniature flat plate specimens have been compared with testing results of cylindrical specimens with standard size and at the same time the comparison has shown a good agreement of the results. The data analysis has also shown the high repeatability of the tests results of miniature specimens. Thus, the developed technique of the miniature flat plate specimens testing could be considered as accurate and reliable method and could be definitely used for evaluation of the tensile properties of the metal.

LONG-TERM OPERATION OF DOSIMETRY FACILITY «PILLE» ONBOARD THE ISS

2021 ◽  
Vol 55 (4) ◽  
pp. 86-90
Author(s):  
V.G. Mitrikas ◽  
◽  
E.G. Khorosheva ◽  
Keyword(s):  
Dose Rate ◽  
Absorbed Dose ◽  
Radiation Monitoring ◽  
The Other ◽  
Radiation Doses ◽  
Absorbed Dose Rate ◽  
Term Operation ◽  
Low Radiation Doses

Malfunctioning of the reader is likely to be the reason for low radiation doses measured by the Pille dosimeters over the more than 20 years of ISS. Rectified measurements of the average daily absorbed dose rate agreed satisfactorily with readings of the other onboard tools of radiation monitoring.

Microstructure and Mechanical Properties of G17CrMoV5-10 Cast Steel After Regenerative Heat Treatment

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Grzegorz Golański
Keyword(s):  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Strength Properties ◽  
Optimum Combination ◽  
Austenitizing Temperature ◽  
Energy Increase ◽  
Regenerative Heat ◽  
Term Operation

This paper presents the results of a research on the influence of regenerative heat treatment on microstructure and properties of a cast steel after long-term operation at the elevated temperature. The material under investigation was G17CrMoV5-10 cast steel taken out (in the form of a section) from an internal frame of steam turbine serviced for about 250,000 h. Performed research has proven that through the microstructure degradation long-term service contributes to an embrittlement and decrease in yield strength and tensile strength. The heat treatment, however, contributes to an impact energy increase regardless of the applied parameters (cooling rate). It has also been established that the optimum combination of strength properties and impact energy is ensured by the microstructure of high tempered bainite, whereas low strength properties and impact energy were obtained for the microstructure, which was slowly cooled from the austenitizing temperature, i.e., the ferritic-bainitic-ferritic microstructure.

Study on control of micro-pollutants by BAC filtration

2008 ◽  
Vol 58 (3) ◽  
pp. 677-682 ◽  
Author(s):  
Z. H. Zhang ◽  
L. Shao
Keyword(s):  
Contact Time ◽  
Continuous Operation ◽  
The Other ◽  
Formation Potential ◽  
Term Operation ◽  
Correlative Analysis ◽  
Trihalomethane Formation Potential ◽  
One Year ◽  
Micro Pollutants

The objective of this research was to evaluate removal efficiency of micro-pollutants in a BAC filter that followed ozonation for long term operation. The experimental results showed that after continuous operation for one year BAC filter still maintained a removal of 15 ∼ 20% for CODMn and 20 ∼ 30% of removal for UV254. Correlative analysis based on lots of data found that empty bed contact time (EBCT) instead of flow rate could obviously impact on removal effect of micro-pollutants in BAC filter. And the optimal relationship between EBCT and removal effect of micro-pollutants for BAC filter was logarithm. On the other hand, long term running of BAC filter proved that there was a good removal of chloroform formation potential, but the removal of brominated trihalomethane formation potential decline with further bromization, even there appeared to be formation of bromoform in BAC filter.

scholarly journals Stereological Evaluation of Precipitates within Ferrite Grains in Heat-Treated 1.25Cr0.5Mo Steel Previously Exposed to Service

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Rafael Fernández-Fuentes ◽  
Americo Scotti ◽  
Amado Cruz-Crespo ◽  
Roberto Silva González ◽  
Rafael Ariza Gonçalves ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Volume Fraction ◽  
Digital Images ◽  
Post Weld Heat Treatment ◽  
Aged Material ◽  
Term Operation ◽  
Heat Treated ◽  
Service Operation ◽  
Weld Heat

The objective of this work was to study the effect of the heat treatment and further operation aging on the stereological parameters (size, quantity and volume fraction) of precipitates within ferrite grains of a creep-resistant 1.25Cr0.5Mo steel after long-term operation. The heat treatment was similar to the treatment that is carried out in industrial steam pipelines after welding (post weld heat treatment - PWHT) during installation and/or repairing. The operation aging corresponds to a subsequent long in-service operation after repairing. To determine the stereological parameters, SEM digital images were taken from samples of this material after conditions of in-service-aged (after long-term operation), in-service-aged and heat-treated (simulating repairing) and in-service-aged, heat-treated and in-laboratory aged (simulating subsequent long-term operation after repairing). The results indicate that the changes in the stereological parameters of the precipitates within ferrite grains after PWHT is associated with the coarsening process of the within-ferrite-grain precipitates as well as stabilizing the microstructure, since the material aging after PWHT of an in-serviced aged material would not change the stereological parameters.

scholarly journals Investigation of Gold Electrodes Surface Condition of Plasma Reactor

2019 ◽  
Author(s):  
Sebastian Gnapowski ◽  
Elżbieta Kalinowska-Ozgowicz ◽  
Mariusz Sniadkowski ◽  
Aleksandra Pietraszek
Keyword(s):  
Plasma Concentration ◽  
Supply Voltage ◽  
Plasma Reactor ◽  
Surface Condition ◽  
High Energy ◽  
The Other ◽  
Term Operation ◽  
Solid Gold ◽  
High Energy Electrons

During the long-term operation of the plasma reactor, decreases in the plasma concentration were noticed despite the constant maintenance of all parameters. One of the factors is the decrease of the nitrogen content on the surface of the electrode, in order to eliminate it, the supply voltage has been increased to 11 kV. The next decisive factor in the decrease of plasma concentration is the oxidation of the electrode surface, therefore two electrodes were used: first one with solid gold and the other one copper covered with galvanized gold with a thickness of 10 μm. During the experiment, a large decrease in plasma concentration was observed when the electrode coated by gold was used. High-energy electrons have knocked out the gold atoms from the electrode, as a result of which the gold evaporated and the raids layers formed. After a month of working of the electrodes, metallographic researches were carried out, the results of which are described in this publication.

Removal of pharmaceutically active compounds in nitrifying–denitrifying plants

2005 ◽  
Vol 52 (8) ◽  
pp. 9-14 ◽  
Author(s):  
S. Suárez ◽  
M. Ramil ◽  
F. Omil ◽  
J.M. Lema
Keyword(s):  
Small Extent ◽  
The Other ◽  
Experimental Unit ◽  
Pharmaceutically Active Compounds ◽  
Removal Rates ◽  
Active Compounds ◽  
Term Operation ◽  
Activated Sludge System ◽  
Wide Range

The behaviour of nine pharmaceutically active compounds (PhACs) of different diagnostic groups is studied during a nitrifying–denitrifying process in an activated sludge system. The compounds selected cover a wide range of frequently used substances such as anti-epileptics (carbamazepine), tranquillisers (diazepam), anti-depressants (fluoxetine and citalopram), anti-inflammatories (ibuprofen, naproxen and diclofenac) and estrogens (estradiol and ethinylestradiol). The main objective of this research is to investigate the effect of acclimation of biomass on the removal rates of these compounds, either by maintaining a high sludge retention time or at long-term operation. The removal rates achieved for nitrogen and carbon in the experimental unit exceed 90% and were not affected by the addition of PhACs. Carbamazepine, diazepam and diclofenac were only removed to a small extent. On the other hand, higher removal rates have been observed for naproxen and ibuprofen (68% and 82%), respectively.

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